Washington and Bahgdad
— The US Marine Corps' MV-22 Osprey, the tilt rotor plane that flies like both a helicopter and a plane, is expected to face one of its biggest tests ever this month, flying combat missions for the first time – a major milestone in the Osprey's long history of ups and downs.

After years of investment, controversy, and tragedy, the Osprey finally debuted this fall in Iraq, a low-key deployment of 10 planes that marks the beginning of the Corps' gradual replacement of aging Vietnam-era helicopters.

Commanders have limited the plane's operations to simpler logistical roles. But now it is set to fly combat missions in Anbar Province, where marines are deployed, that will test the plane's ability to maneuver in more sophisticated and dangerous combat missions. The awkward-looking hybrid has two large propellers mounted on nacelles that swing up and down to allow it to take off and land like a helicopter and to fly like a plane. The Osprey's deployment to Iraq has already shown that some components of the complex plane wear-out faster than others. But generally, it's so far, so good, says the Corps' top officer.

"It's a learning experience, and that's why we deployed it here, and part of it was to be able to see just how it performs in combat," says Commandant Gen. James Conway, during a recent trip to Iraq to see the Osprey. General Conway says there is still much to learn, but that he likes what he sees. "What I saw ...is that it is going very well."

The Corps has staked much on the future of the Osprey, which has taken decades to develop and is blamed for the deaths of 23 marines in two separate accidents in 2000. Despite the high-profile nature of the plane, Corps officials have played down its arrival in Iraq this fall.

That may change as marines prepare to employ it in a series of missions called "Aeroscout," in which they use ground and air assets to swarm suspected insurgent and terrorist targets, says Marine Lt. Gen. George Trautman, who heads the Corps' aviation division. General Trautman says the Osprey, which flies faster and farther than the CH-46 Sea Knight helicopter it replaces, will allow Corps commanders to conduct more combat missions than they could before.

Trautman conceded that the combat role for the Osprey would be somewhat limited, as much of the insurgency has left the once-dangerous province. Currently, the Osprey is used for "assault support," says one official in Iraq.

But early on in its deployment that began in October, one plane had to make an emergency landing in Jordan and daily reports showed that its "readiness rates" had slipped to as low as 40 percent on one day – 50 percent on two other days. Those lower rates were largely driven by a dearth of replacement parts when Corps officials saw how some components wore out faster in the desert climes of Iraq, where the sand is finer than almost anywhere in the US. Now that Marine officials have been able to identify those parts and get sufficient replacements in stock in Iraq, those readiness rates have climbed back up to close to what Corps officials say is a more comfortable 80 percent.

"It's one thing to use engineering models and forecasting, and it's another to actually run the airplane in that environment," says Trautman. "You're on a learning journey, there is no doubt about that."

Recent media criticism of the plane included the concern that it has no side- or front-mounted weapons systems, leaving it vulnerable to attack. But Trautman says the Corps is looking at a belly-mounted, "all-aspect" gun that would have a 360-degree firing capability.